1. Field of the Invention
The present invention relates to telephony services. More particularly, but not exclusively, the present invention relates to systems and methods for providing persistence of an interrupted call in a telephony network.
2. Description of the Background Art
Wireless communication technology has allowed individuals considerable freedom in how and when they communicate with each other. Analog signal-based cellular telephone technology, which allows people to travel freely while always having access to a telephone, has grown and developed into digital-based systems and hybrid telephone/multifunction devices so that a number of functions are now provided in a single integrated device.
One inconvenience frequently experienced by cellular users today is the interruption of mobile calls as a result of a short network disconnection. Usually, the short network disconnection occurs when a cellular user passes through areas with low coverage of the Cellular Networks. The short network disconnection may also occur on a temporarily coverage blocking, or upon interferences over the transmission lines between the cellular user's mobile unit and a serving cellular antenna (BTS) of the cellular telephony provider.
For example, a cellular user may experience a short network disconnection when entering an elevator in a large office building, while having a cellular call. Elevators often cause a disconnection between a mobile handset and its serving cellular antenna (BTS), due to the low level of the RF (Radio Frequency) Signal received from the mobile unit at the serving cellular antenna (BTS), when the cellular user is in the elevator.
Many attempts have been made to improve the quality of service experienced by a cellular user.
U.S. Pat. No. 6,360,109 issued to Thauvin et al, entitled “Terminal, Automatic Recall Procedure, and Telecommunication System,” filed on Apr. 22, 1998, and hereby incorporated by reference in its entirety, discloses a terminal, an automatic recall procedure, and a telecommunication system, which include means for integrating an automatic repeat call function in a terminal of a telecommunication network. The terminal described by Thauvin is provided with a data transfer protocol which operates in a simultaneous bidirectional mode. The automatic repeat call function is realized by a device integrated in a local terminal.
The local terminal is provided with a command to be triggered after an effort to achieve a connection to a distant terminal has failed. The object of the command is to automatically repeat the effort until the connection has been established. However, the repeated effort to achieve a connection is limited by a given number of repeated attempts.
That is to say, the automatic repeat call function has to be installed in each and every mobile terminal of a subscriber of an automatic repeat call service, as described by Thauvin.
U.S. Pat. No. 6,782,268 issued to Thompson et al, entitled “Method and Apparatus for Tracking Call History for Mobile and Wire Line Users Accessing the Network on Different Ports for Subsequent Calls,” filed on Jun. 23, 1998, and hereby incorporated by reference in its entirety describes a method and a system for associating call data with particular users instead of line ports. The call data includes the last incoming and outgoing calls associated with a particular number. Consequently, there are allowed services, such as automatic callback, automatic recall, and customer originated trace, to be implemented with dynamic line assignment allowing users to maintain the same level of subscribed services at different locations.
U.S. Pat. No. 6,393,272 issued to Cannon et al, entitled “Wireless Answer and Hold Feature,” filed on May 21, 2002, and hereby incorporated by reference in its entirety describes a telephone including an answer and hold feature. Using the answer and hold feature, in response to a user input, the telephone answers an incoming call, issues an outgoing greeting message, and maintains a connection status. Thus, the called party may unobtrusively cause the call to be held in the connected status until a time when the called party can conveniently enter into a conversation.
U.S. Pat. No. 6,999,572 issued to Shaffer et al, entitled “Automated Call Connection System,” filed on May 1, 1998, and hereby incorporated by reference in its entirety relates to automatically connecting calls, and more particularly to an improved, automated system and method for connecting multi-media calls. Shaffer describes a call back method where a first user may request a second user to call him back, and the two sides may be automatically connected.
U.S. Pat. No. 6,973,317 issued to Dolan, entitled “Call Completion Based on Movement of Mobile Station,” and filed on Dec. 18, 2000, and hereby incorporated by reference in its entirety describes a callback service for completing a call from a calling party to a mobile station of a called party. The Dolan Patent relates to a call previously failed due to no response. After the call fails due to no response, the mobile station of the called party is monitored to determine if the mobile unit is moved to another cover area of the network, and when such movement is determined to occur, a callback is initiated between the calling party and the called party.
U.S. Pat. No. 6,456,842 issued to Subramanian et al, entitled “System and Method for Subscriber-Controlled Call Back on Busy in a Cellular Network,” filed on Sep. 13, 1999, and hereby incorporated by reference in its entirety describes a telecommunications system and method for allowing a calling mobile subscriber to activate a call back on busy feature and specify the maximum waiting period after which the call back is no longer attempted. Upon reception of a busy indication at an original Mobile Switching Center/Visitor Location Register (MSC/VLR) serving the calling mobile subscriber, the original MSC/VLR plays an announcement to the calling subscriber to collect the time interval beyond which the network should cease to attempt the call back.
None of the above patents describes a method for overcoming the inconvenience experienced by cellular telephony users when a mobile phone call is interrupted as a result of a short and unintended disconnection. There is thus a widely recognized need for, and it would be highly advantageous to have, a system devoid of the above limitations.